Question: When was prime minister first mentioned in a government document in the country Prince of Thieves, whose main character John is depicted alongside, made?
Context: Document 1: Robin Hood: Prince of Thieves: Principal exteriors were shot on location in the United Kingdom. A second unit filmed the medieval walls and towers of the Cité de Carcassonne in the town of Carcassonne in Aude, France, for the portrayal of Nottingham and its castle. Locksley Castle was Wardour Castle in Wiltshire -- restored in an early shot using a matte painting. Marian's manor was filmed at Hulne Priory in Northumberland. Scenes set in Sherwood Forest were filmed throughout England: Burnham Beeches in Buckinghamshire was used for the outlaws' encampment, Aysgarth Falls in Yorkshire for the fight scene between Robin and Little John, and Hardraw Force in North Yorkshire was the location where Marian sees Robin bathing. Sycamore Gap on Hadrian's Wall was used for the scene when Robin first confronts the sheriff's men. Chalk cliffs at Seven Sisters, Sussex were used as the locale for Robin's return to England from the Crusades.
Document 2: Boys' Brigade Gazette: The Boys' Brigade Gazette is a quarterly magazine printed regularly since 1889 in the United Kingdom for the officers and leaders of the Battalions and Companies of the Boy's Brigade in the UK and Ireland.
Document 3: John, King of England: Nineteenth-century fictional depictions of John were heavily influenced by Sir Walter Scott's historical romance, Ivanhoe, which presented "an almost totally unfavourable picture" of the king; the work drew on Victorian histories of the period and on Shakespeare's play. Scott's work influenced the late 19th-century children's writer Howard Pyle's book The Merry Adventures of Robin Hood, which in turn established John as the principal villain within the traditional Robin Hood narrative. During the 20th century, John was normally depicted in fictional books and films alongside Robin Hood. Sam De Grasse's role as John in the black-and-white 1922 film version shows John committing numerous atrocities and acts of torture. Claude Rains played John in the 1938 colour version alongside Errol Flynn, starting a trend for films to depict John as an "effeminate ... arrogant and cowardly stay-at-home". The character of John acts either to highlight the virtues of King Richard, or contrasts with the Sheriff of Nottingham, who is usually the "swashbuckling villain" opposing Robin. An extreme version of this trend can be seen in the Disney cartoon version, for example, which depicts John, voiced by Peter Ustinov, as a "cowardly, thumbsucking lion". Popular works that depict John beyond the Robin Hood legends, such as James Goldman's play and later film, The Lion in Winter, set in 1183, commonly present him as an "effete weakling", in this instance contrasted with the more masculine Henry II, or as a tyrant, as in A. A. Milne's poem for children, "King John's Christmas".
Document 4: Prime minister: The United Kingdom's constitution, being uncodified and largely unwritten, makes no mention of a prime minister. Though it had de facto existed for centuries, its first mention in official state documents did not occur until the first decade of the twentieth century. Accordingly, it is often said "not to exist", indeed there are several instances of parliament declaring this to be the case. The prime minister sits in the cabinet solely by virtue of occupying another office, either First Lord of the Treasury (office in commission), or more rarely Chancellor of the Exchequer (the last of whom was Balfour in 1905).
Answer: first decade of the twentieth century
Reasoning steps: Who was John depicted alongside? Answer: Robin Hood
where was Robin Hood prince of thieves made Answer: the United Kingdom
the United Kingdom >> follows Answer: UK
When was prime minister first mentioned in a government document in the UK ? Answer: first decade of the twentieth century